This invention relates to the total synthesis of the known antibiotic thienamycin (I). ##STR3##
Starting from L-aspartic acid, the synthesis proceeds in a stereo-selective way via intermediates II, III, IV: ##STR4## wherein X is a conventional leaving group and R is hydrogen, a conventional, readily removable protecting group or a salt cation. This invention also relates to a process for preparing III via intermediate V: ##STR5## wherein R is a protecting group.